The present invention relates, in general, to a method and apparatus for testing pressure sensors and, more particularly, to a method and apparatus for high pressure testing of solid state pressure sensors.
Solid state pressure sensors are comprised of a diaphragm die (or wafer of dice) being coupled to a base die (or wafer of dice) leaving a cavity disposed therein. As the surrounding pressure changes, the diaphragm flexes causing a change in the electrical properties of the diaphragm. These electrical properties are measured and used to provide a value indicative of the pressure being exerted on the die.
Presently, solid state pressure sensors are tested after final assembly of the devices. This means that the manufacturer has already borne most of the cost of production before a device can be evaluated as to its usefulness.
To test the devices, they are placed in a pressure chamber that also contains the testing equipment. This type of testing device, because of the high pressures at which it operates, can be hazardous. This method of testing devices also takes a great amount of time waiting for the pressure to be raised before the testing and lowered after the testing. This technique requires the use of a large, relatively expensive pressure chamber.